They could tie attraction and skill talents to a zodiac. Both are features that do not dictate my sims' life, but if they decide to act in accordance with their zodiac-granted strengths, they have an easier time.
For comparison, in Sims 2 free time, having negative attraction with another sim only makes romancing that one harder. After the first succesful date the neagtive bolt is erased and replaced by a single positive bolt. And all a sim's "one true hobby" (that is predetermined by their personality, so also connected to their star sign) does is making progress in that hobby faster. The sim can still decide to take up a different one, earn the genie lamp and the membership cards to the secret lots.
